OVERCOMING THE VAPORS

By Julian Moynahan; Julian Moynahan has recently completed a book on English-Irish writers. He is at work on a novel set during World War II.

Published: June 12, 1988

NOT THAT SORT OF GIRL By Mary Wesley. 279 pp. New York: Viking. $17.95.

BORN in 1912, Mary Wesley didn't publish her first novel until she was 71. Since then she has brought out four more, including the latest, ''Not That Sort of Girl,'' which was a finalist last December in the Sunday Express's Book of the Year competition in Britain. Penguin is issuing paperback editions in the United States of two of her earlier titles, ''Jumping the Queue'' and ''The Vacillations of Poppy Carew'' ($6.95 each), to go with this one and to introduce her more broadly to American readers. Despite the late start, Ms. Wesley is certainly no Grandma Moses of literature. Far from being a primitive, she is, rather, a skillful, contemporary British realist with a distinctive voice and a penetrating eye for the various corruptions and follies of the London and Home County middle-class people who are her principal subjects.

Ms. Wesley is of the English middle class herself. And so the characters in these novels are often judged, for example, by how well they treat their house pets and other domestic animals. But she pushes things to excess in an imaginative, sometimes idiosyncratic way. (Matilda Poliport, the 50-year-old widow in ''Jumping the Queue,'' has a passion for a gander named Gus and the handsome bird feels pretty much the same about her.) In each of these books an important incident is staged at the sinuous lake in London's Hyde Park called the Serpentine: someone gets killed there or betrayed or swept away in passion. Mary Wesley also likes to play about with suspicions of incest. Whether this reflects a lifetime of reading lending-library romances or entails a perception that those who overvalue property may not want that to go out of the family either is difficult to say.

Ms. Wesley's characters are utterly secular minded. They don't like nurses, hospitals or the National Health, and they aren't wild about the police either. Her heroines tend to be virgins or near-virgins when they marry; they fall out of love with their husbands rather quickly and, in time, make resourceful, self-reliant, if not ecstatically happy widows. These features reflect the time the novelist has lived through and the slowly altering social experience of the group to which she is attached. Everything else derives from her talent and imagination.

Her first book, ''Jumping the Queue,'' has a tightly wound, rather desperate plot to go with its punchy title. Its main male character is called the Matricide because he has bashed his old mother with a heavy silver tray and is on the run from the police. He is actually a very decent sort, though apt to let shyness and shame overrule his better judgment. This book is an excellent introduction to the bitter tonic of Mary Wesley's fictive imagination.

''The Vacillations of Poppy Carew'' is largely set in the Downs region, among young people who in all likelihood are the descendants of those Kentish and Suffolk villagers who got punched out by the Invisible Man or lasered to death by the Martian machines in the early scientific romances of H. G. Wells. But the age of Wellsian marvels has passed and these descendants are more into pig farming, restoration chic and an undertaking business managed by ex-hippies that features vehicles drawn by coal-black steeds with nodding sable plumes. I wasn't won to this book as I was to ''Jumping the Queue.'' The young are not really Ms. Wesley's thing, so one gradually loses interest - after a tough and funny death scene staged in a hospital geriatric ward - in the question of whom Poppy will choose to marry after she stops vacillating.

''Not That Sort of Girl'' has as its purview the last half-century and is told from the viewpoint of Rose Peel, an elderly widow who has just lost a husband and faces the intriguing problem of whether she should unite herself at last with a half-French, half-English lover, Mylo, who has been in and out of her bed during the greater part of her marriage without anybody ever catching on. It's a bit unbelievable, of course. During World War II the lucky fellow was an intelligence courier and would climb up Rose's trellis on his way home from undercover missions in France, always coming and going by night. (In the neighborhood where I grew up, this would be called nice work if you can get it.) At the time, young and comely Rose was in charge of her husband's country estate while he officered in a county regiment before getting promoted to the General Staff.

''Not That Sort of Girl'' is an uneasy mix of romance and realism, but it has some fascinating bits about the last big war, especially about wartime London. Rose's mother has a hypochondriacal husband who, just as the war begins, succumbs to heart trouble instead of the cancer he had always feared. His widow, a bridge-playing Tory given to depressions and nervous vapors, moves straight to London and starts buying flats dirt cheap during the days of the Dunkirk retreat and the German bombing blitz. She would never buy Hampstead property, however, because of the rumor that the enemy dropped more bombs up there owing to Hampstead's large number of Jewish residents.

REMOTE as they are from the heroics of Churchill's wartime speeches, such details ring true, if only because we know that big wars give women a chance to get out of the house and do their stuff unhampered by the male prejudices and browbeatings of their spouses and brothers. Of course, women get knocked back when the troops come home, but not women who have learned to live alone and who are owners of large chunks of London real estate.